Furnace



W. A. OGG

July 7, 1936.

FURNACE Filed Feb. 12, 1934 4 Sheets-Sheet 1 July 7, 1936;

FURNACE 4 sheets-sheet 2 Fil'ed Feb. 12, 1934 mmm July 7, 1936.

w. A. OGG

FURNACE Filed Feb. 12, 1954 IQ R 4 Sheets-Sheet 3 July 7,1936. w. A. OGG 2,046,402

FURNACE Filed Feb. l2, 1954 4 Sheets-Sheet 4 Patented July 7, 1936 UNITED STATES PATENT OFFICE 'I'his invention relates to furnaces and the object is to provide an improved construction of furnace ofthe indirectly heated'type. A more particular object of the invention is to provide a furnace for the reduction of zinc adapted for the practice in a particularly eicient manner of 'the process of zinc smelting described in my United States Patent 1,925,458, September 5,

My invention will be well understood by reference to the following description of the particu- 'lar embodiment thereof shown by way of example in the accompanying drawings, wherein:-

Fig. 1 is a broken-longitudinal section of the furnace;

Fig. 2 is a plan section substantially onY the line 2 2 of'Fig. 4; 1

Fig. 3 is a section on the line .of Fig. 2;

Fig. 4 is a transverse section, the lower portion being along the line l-la of Fig. 2 andthe upper portion along the line 47th; Y

Y. Figs.` 5 and are side and endelevations respectively ofa. roof'tile; p Fig. 7 .is a fragmentary View showing the charging mechanism in vertical section; and

Fig. 8 is asection of a condenser taken on the line 8-8 of Fig. 1.

In the embodiment of my invention shown the furnace comprises a. series of longitudinally adjacent, long and narrow reaction chambers 9, as best seen in Fig. 2, six such chambers being here illustrated but by way of example only, which chambers have-roofs I I, preferably of a construction to be hereinafter more speciiically described, formed of heat-resisting material of high heatconducting capacity. Charge material, preferably as recommended in my patent above referredto consisting of a thin layer l/2 inch or less in thickness of a mixture of crudezinc oxide with' substantially only suflicient carbon theoretically necessary to eiect the reducing reaction, may be supported in thechambers in opposition to the roofs II by. means of pallets or tables I3 of substantially the vsame plan area as the chamber, which may be introduced into the reaction chambers from one end thereof. Two such tables are shown in position in the upper two reaction chambers in Fig. 2 and in the case of themiddle two reaction chambers they are shown withdrawn. A- vapor offtake I5 which may lead to a condenser, such, for example, as that shown in Fig. 1 hereinafter to be more fully described, may be provided at the opposite end of the reaction chamber.

Referring now more particularly to Fig. 4, over the roofs I I of the reaction chambers is a combustion chamber Il defined by the overlying roof I9 of the furnaceasawhole. Accessto thecomhustion chamber may be had through doors 20, (Fig. 4). In this combustion chamber fuel is bumed to heat highly the roofs II, transmitting heat therethrough to be radiated from the inner surfaces thereof to the underlying charge. The

furnace `shown in the drawings is heated by means of oil fuel and I have shown at either end of the combustion chamber openings ZI by which oil is introduced to be burned in the combustion chamber, preferably with preheated air. For this purpose a suitable regenerating system is provided and that herein illustrated has particu 15 as the reaction chambers 9 and at right angles.

to the regenerative chambers 23 and 25 to a remote point where they communicate with the vertical stacks35 in the form of Venturi tubes. The regenerative chambers are provided with, suitable checker-work as indicated Across the throat of each tube is provided a damper 31 and air may be furnshedto the tubes by means of a suitable motor-driven blower 39. In operation the damper of that one of the tubes 35 through which the products of combustion are to be ex\ hausted to atmosphere is open and the damper of the other is shut. Air furnished by the blower to the closed tube is thus forced throughA the ap, propriate auxiliary regenerative chamber and corresponding main regenerative chamber wherein it is highly heated and on reaching the combustion chamber I'I at one end of the block of retorts burns with the fuel, passing over' and transferring heat to the roofs II of the reaction chambers. Assuming by way of example that the heated air hasA thus been introduced at the left in Fig. 4, the products of combustion leave at the right-hand end of that figure and pass through the down-take to regenerative chamber 25 and auxiliary regenerative chamber 33, finally reaching atmosphere through the open Venturi stack. After the lapse of a suitable interval the dampers are reversed and the flow. of combustion air and heating gases is then in the opposite direction.

To insure effecting heating of the charge the roofs of the combustion chambers must be' Aheat-resisting material consisting essentially of silicon'carbide. A material of this nature is well known commercially under the trade name of Carbofrax. While the -heat is applied to the charge by radiation from the inner surface of the roof, the transfer lof heat to that radiating surface is, of course, by conduction through the material of the roofv which is dependent upon the area. of the roof and its thickness. To provide for adequate heat transfer while providing a large margin of safety for structural strength and wearing qualities in the roof I preferably so construct it that with a substantially uniform thickness its surface area is markedly in excess of its projected area, the roof thus having a generally corrugated form. Herein the roof is formed of tiles a (see Figs. 5 and 6) which might be described as of basin-like form or otherwise as in the form of a hollow frustum of a pyramid. Preferably their length is such as to bridge across from one side wall of a reaction chamber to another, as seen in Figs. 2 and 4, and their longitudinal edges may be provided with the tongues 4| and grooves 43 permitting them to be joined together in a series longitudinal-of the chamber to form a complete roof, as seen in Fig. 2. This arrangement not only provides for a greatly increased transfer of heat as compared with a fiat roof, whereby for a given thickness of tile adequately high temperatures can more readily be attained at the radiating surface, but the shape d disclosed obviously provides substantial structural strength in the tile itself permitting a relatively thin Wall to be used with safety.

'I'he construction of the furnace in the manner described with the auxiliary regenerative charnbers extending to a remote point of control provides for its organization within a limited space and, as seen in Fig. 2, between the reaction chambers proper and the Venturi stacks at space is provided for the installation of the charging mechanism which will next be described.

Referring to Fig. 1, the table |3 which supports the ,charge in the reaction chamber, when withdrawn from the same, is received within an aligned gas-tight antechamber,` here shown as comprising two parts and 41. A door 49 constructed of refractory and insulating material may be arranged between the reaction chamber 9 and the antechamber and may be moved up and down by means of a chain or wire rope 5| leading to hand wheel 53. The main purpose of this door is to prevent the loss of heat by radiation from reaction chamber 9 to antechamber 45. By means of suitable guides this door may be made to t reasonably close to the end of the retort,- but a gas-tight seal is not intended or required. 'I'he table |3 may be built up from suitable'shapes of insulating and refractory materials which may be supported by short cross-members of chromium iron alloy and is here shown as carried at one end on an I beam 55, at least the inner portion or left-hand portion viewing Fig. 1 of which may be constructed of chrome iron and which extends outwardly or to the right in the figure along the longitudinal center line of the table for a suit-- able distance. This beam constitutes, a skid which may travel in a groove 51 (see Fig. 4) in the bottom of the reaction chamber! and herein also in. the bottom of the antechamber 45 by means of which thetable is moved back and forth into and out from the reaction chamber. For this purpose the upper surface of the rearwardly extending end of the beam may be formed as a rack, as best seen in Fig. 2, with which meshes a pinion 59 driven by a reversible motor 6| (Fig. 1). The provision of the gas-tight antechamber enclosing the table in its withdrawn position and also including the portion.4`| enclosing the extension of the beam prevents loss'of vapor and of heat from the retort during movements of the table and excludes air from the reaction chamber. l

The table I3 is provided with charge material when withdrawn into the antechamber. 'Ihus in practising the process described in my previous patent above referred to, a layer of crude zinc oxide and substantially only enough carbon theoretically necessary to` eiect'the reducing reaction is applied thereto in a thin layer say 1/2 :i l

inch in thickness or less. To supply charge material on the table I3 in a layer of uniform depth the charging mechanism shown in Fig. 7 may be conveniently utilized. This comprises a hopper B3 delivering to a measuring wheel mechanism which in turn discharges to a spout 61 passing through the upper wall of antechamber 45 adjacent the forward end thereof so as to deliver material upon the forward end of table |3 in its withdrawn position as shown in the figure, the il" spout 61 being joinedto the wall of the chamber through a suitable gas-tight seal 69. 'I'he hopper 63 is at all times kept well filled with charge material to prevent entrance of air to the chamber 45 and the measuring wheel of the measuring 3` mechanism is divided into a number of segments extending substantially the width of the table and of such size that each contains the quantity of charge material intended for one layer. When the measuring wheel is rotated through 'an angle equal to one segment, the charge contained in one segment will be discharged through 61 onto the forward end of the table I3. In the form of the invention shown the front wall Il of this spout is cut away to the same depth as thatof the charge layer to be applied and it thus constitutes a regulator or strickle plate so. that when the table |3 is advanced toward the left in Fig. 7 the material in the spout will be spread over the surface thereof in a layerequivalenl; to the clear- 501 layer of charge is small andz sucssive charge 60 layers may be reduced before the residue accumulates to a depth requiring its removal. It is' evident that if the residue be thus removed at infrequent intervals it will be necessary as fresh layers are applied to raise the strickle plate Il to 65y compensate for the depth of residue remaining on the surface of the table. Herein the entire charging unit is vertically movable on guides 13 and may be adjusted by means'of the suspending screw 15 manipulated by hand whed 11. f 70 When the residue has reached a depth on the table where its removal is advisable,` the'table-is withdrawn from the reaction chamber into the Y antechamber and the doorfclosed. The residue may then be discharged from the table by means from opposite side walls in internested relation of any suitable equipment introduced, for instance, through an end door 18 as shown in Fig. 1. After the residue has been discharged reducing gas maylbe introduced into the antechamber before the next charge layer is applied to the table.

The reduction of successive' charges in this manner due to a minimum accumulation of residue is facilitated by the fact that it is unnecessary to limit the temperature in .the reaction chamber to avoid slagging.' Slagging is no detriment to eilicient operation and to some extent may even be advantageous. Thetemperature in the reaction chamber may be such that theslag is liquid and may be permitted to flow over the edges of the table i3 which has a slight clearance from` the walls of that chamber to permit this, as seen in Fig. 4, and the slag may fall into slag channels 19 which,ras seen in Fig. 1, are sloped to permit it to drain toward a pocket 8l from which it may be tapped at suitable intervals through a tap hole 83. The spaces at the sides of the table permit transfer of heat from the radiant roof to the slag in the slag channel so that the slag will at all times be fluid.

Instead of leaving a space between the side edges of the tables and the walls and. letting the slag drip over the sides, the surface of the table may slope slightly from each side toward the center so as to deilne` a sortV of gutter or channel in the center, which itself slants toward the front of the table (left-hand end in Figs. 2 and 1). A layer of coke breeze fills this channel and provides a level surface for the table on which the charge material may be deposited. As slag forms, it will trickle through the underlying coke layer and drain toward the centerrand thence to the forward end of the table and over the front end thereof to the slag pocket.

The vapors distilled pass through the oitakes l5 and, in case spelter is to be made; pass to a suitable condenser. I vhave shown a condenser in the present disclosure by way of example. In order to reduce any carbon dioxide gas in the gases formed to carbon monoxide the vapors rst pass through a body of coke 85 maintained at a high temperature by radiation from the interior of the retort through the vapor port l5. The vapors then pass to the condenser proper which for purposes of description may be divided into 'a rst or baiile section and a second or scrubbing section. The top and side walls of these sections are thin and may be formed of steel plates coated on the interior with a refractory cement so that the zinc cannot attack the steel and eat it out. As best seen in 8, the baille section 81 is provided with a number of baiiies extending which force the vapors to take a tortuous course during which they are considerably cooled and some liquid may be deposited on the sloping bottom of this section to gravitate toward the left viewing Fig. 1. These bales 81 may likewise be steel plates coated with refractory cement. The scrubbing section comprises a multiplicity of metal rods 89 of steel or copper arranged in quincuncial relation as Yshown which depend through the roof of the chamber. vThe inner ends of these rods are also suitably treated with refractory cement to prevent attack by the zinc. The upper ends of the rods are desirably bare and are exposed above the upper wall of the condenser toar so that they are eiciently cooled. I'he quincuncial or staggered relation of these rods compels the vapors to impinge upon them to be conjdensed thereby and the condensed metal drips therefrom to the bottom of this section of the condenser fromwhich it may be withdrawn as desired through tap hole 9|. 'I'he gases escape through an oiItake 93.

To further facilitate the understanding of the invention but without limitation to these specific dimensions, I may say that suitable -dimensions for the. charge tables I3 might be 10 feet long and 3 feet wide and the clearance between the A upper surfaces of these tables and the lower points of the roof Il about 4 inches.

The furnace as described makes possible the practice of the process described in my Patent No.

1,925,458 first referred to in a manner realizing fully the advantages thereof. The furnace is compact and requires a small capital investment for its capacity. As contrasted with the now almost universal process of zinc smelting by means of so-called Belgian retorts, the manual labor required is greatly reduced. At the same time a purely theoretical, large scale construction which would introduce factors adversely aiecting the eiciency of the process is avoided. Thus, for instance, in indirectly heated furnaces as at present known other than the ordinary Belgian retort furnace with its well known disadvantages, severe limitations upon the heat transmissible wereimposed by reason of the general requirement that it be transmitted through relatively thick walls. In the construction described the roofs II of the reaction chambers may be suiiiciently thin eiliciently to conduct the necessaryy amount of heatto the inner surface'th'ereof and the reduction process may be carried on rapidly on account of the high temperature applied to the charge without encountering those disadvantages which in the case of the Belgian retort process Y have been encountered when temperatures were substantially increased. Further advantages willbe apparent to those skilled in the art, particularly, in the case of zinc smeltlng, ,when considered in' connection wit-h my patent above re-r ferred to. t

I am aware that the invention may be embodied in other specific forms'withoutgdeparting from the spirit or essential attributes thereof, and I therefore desire the present embodiment to be considered in all respects as illustrative and not dening a fuel combustion chamber above said roofs, means for. causing heating gases to travel through the combustion chamber, and independent travelling supports each appurtenant to one of the reaction chambersand of area substantially equivalent to the plan area thereof for introducing into the reaction chambers thin layers of charge material in 'opposition to the roof thereof.

prising a series of longitudinally adjacent narrow and shallow reaction chambers having outlets for the vaporized product, the roofs of such chambers being of high heat conductivity, walls defining a fuel combustion chamber above said roofs, means for causing heating gases to travel 2. A furnace for smelting or the like comy through the combustion chamber, gas-tight antechambers in alignment with said reaction chambers, heat intercepting doors between the two last-mentioned chambers, tables of substantially the plan area of the reaction chambers, means for traversing the same between said chambers and means associated with the ante-chamber for depositing charge material on said table to be carried thereby into the reaction chamber for presentation as a thin layer in close opposition to the roof thereof.

3.l A furnace for smelting zinc or the like comprising a series of longitudinally adjacent narrow and shallow reaction chambers having outlets for the vaporized product, the roofs of such chambers being of high heat conductivity, walls defining a fuel combustion chamber above' said roofs, regenerating chambers beneath said reaction chambers communicating with the combustion chamber` at the ends of the series, auxiliary regenerating chambers extending from the rst longitudinally, means at the further ends thereof for controlling the ow of gases through the regenerating and combustion chambers, and charging equipment located in the space between ends of the reaction chambers and said controlling means for individually charging each of the reaction chambers with a thin layer of material to liein opposition to the roof thereof.

4. In a furnace for smelting zinc or the like a long shallow reaction chamber having a bottom forvsupporting a thin layer of charge extended thereover, a roof for the chamber constituting a partition between the sameA and a fuel combustion chamber, said roof comprising a series of tiles of material of high heat conducting capacity of substantially frusto-pyramidal hollow form.

5. In a furnace for smelting zinc or the like a long shallow reaction chamber having a bottom for supporting a thin layer of charge extended thereover, a roof for the chamber constituting a partition between the same and a fuel combustion chamber, said ,roof comprising a series of tiles of material of high heat 'conducting capacity of substantially frusto-pyramidal hollow form and each extending transversely across the chamber. 6. A furnace for smelting zinc or the like comprising a series ot longitudinally adjacent narrow and shallow reaction chambers having outlets for the vaporized product, the roofs of said chambers being of high heat conductivity, the floors of the chambers having longitudinal grooves, skidsI travelling in the grooves, tables of means for traversing them into and out fromA the chambers, loadingv means therefor comprising a device for depositing a measured amountA of charge material at the front end of a retracted table and a vertically adjustable strickle-plate for levelling the same and means for externally heating the roofs of the chambers.

8. A furnace for smelting zinc or the like comprising a series of longitudinally adjacent narrow and shallow reaction chambers having outlets for the vaporized product, the roofs of said chambers being of high heat conductivity, travellng'tables of substantially the plan area of the chambers arranged to enter and leave the chambers at an end thereof, said tables having a clearance from the side walls of the chambers. slag channels at the bottom of the chambers beexterior and means for exteriorly heating said roofs. I

' neath the edges of the table discharging to the 4U 

